Traditional Chinese medicine (TCM) is a system of health care based on the late-twentieth-century standardization of medical practices that originated in China some 2500 years ago. Two classic medical texts, the Nei Jing (compiled from 100 B.C. to 100 A.D.) and the Nan Jing (written circa 100 to 200 A.D.) were important early documents that presented the core concepts of TCM, and they have informed generations of scholars and practitioners ever since. These core concepts suggest that disease is the result of imbalances in the flow of the body’s vital energy, or qi (pronounced “chee”), and that the human body is a microcosm of the basic natural forces at work in the universe.